1. Field of Invention
The present invention relates to a data interface for accessing peripheral devices and personal computers, and in particular to a PCI Express (Peripheral Component Interconnect Express) interface.
2. Description of Prior Art
Universal Serial Bus (USB) is a public interface standard for accessing peripheral devices and personal computers. Recently, the application of USB has been extended to a large number of consumer electronics and mobile devices. Interfaces complying with the specification of USB 2.0 have now been enjoying wide application, since the USB 2.0 interface has a highest speed of 480 Mb/S and also the capability of power supply, which leads to the popularity of the USB 2.0 interface in the current field of PC interface. As storage capacity and network speed enters the epoch of Gigabyte, however, the data connection between PC and peripheral devices requires a higher transmission rate, and USB 2.0 is having difficulty in meeting the continuous growing requirement of access rate. Therefore, there is a pressing need for a new interface specification with respect to data connection between PC and peripheral devices.
A solution is utilizing an eSATA (e Serial Advanced Technology Attachment) interface to lead a SATA interface out of the PC mainframe, and such interface can support a bandwidth of 3 Gb/S. Unfortunately, this solution has drawbacks in that no power supply signal is provided in such interface and thus it is impossible to power the device. In addition, the interface supports only simple storage devices, and thus it is difficult to connect a large number of consumer electronics with the computer via the interface. Further, this solution is not compatible with many existing USB devices.
Another solution is ExpressCard interface being applied widely to notebook computers and capable of supporting a data transmission rate of 3 Gb/S. The ExpressCard interface can supply power to storage devices and support all of PCI Express interface, USB interface and the like. PCI Express interface can be simply referred to as PCIe interface, which inherits the existing PCI communication standard while being based on a faster serial communication system. The ExpressCard interface is divided into two categories of ExpressCard|34 and ExpressCard|54, which appearances are shown in FIGS. 1(a) and 1(b), respectively. As can be seen from the figures, the ExpressCard|34 interface has a large outline size of 75×34 mm, even though it is smaller than the other one. Although the interface has support for USB devices, such support is established on the basis that the interfaces of the USB devices also adopt the specification of ExpressCard interface, while the conventional USB device cannot be supported by the interface. Therefore, it lacks compatibility with many existing devices of USB interface.